It has something do do with the mental state that you are in before you start to play the game. When in gameplay and after gameplay the mental state you were previoulsy in has been altered by the misleading, unclear and unbeleviable ammount of activiety that happend in a short period of time. As a result, confuses you to think "what just happend." although asking your self this question you really dont know the answer untill days, weeks or months from when the game started.

psycological tricks (reverse psychology, etc..) used to gain an advantage on one's adversary. Mind games can be used for casual situations like billiards or intense moments like convincing your boss/teacher that you were, in fact, on time. Invented in 2007 by Los Gatos Soccer head coach Rusty Millard. Not to be confused with Old Greg's "love games."

Rusty, " I was like, "Whatever Matt, I know you wanted to wear your green jersies, well you know what? It doesn't matter, we invented mind games""
Porter "We did not invent mind games Rusty"
Rusty "No, we did, last year"